Tired all the time

Why am I so tired all the time?

In today’s stressful lifestyle, you may think that feeling somewhat tired and weak may be just a sign of stress. However, if you are so tired all the time that daily tasks seem like a burden, you need to seek medical attention.

Medical causes for feeling tired all the time

If you have been wondering, “Why am I tired all the time?”, you need to visit your doctor first and rule out medical causes. I will first list common medical causes of fatigue and describe why they make you feel like you have no energy at all. I will then tell you what blood test your doctor needs to order to find out why you are so tired all the time.

  1. Anemia: Many patients with anemia come to medical attention asking the question “Why am I tired all the time?” Anemia is the reduction of red oxygen carrying hemoglobin in your blood. When your hemoglobin goes down, your body is unable to carry enough oxygen from your lungs to the rest of your body. Each and every organ in your body needs oxygen to function properly. When your body does not get enough oxygen, you feel tired all the time. Women lose blood regularly during menstrual bleeding and can develop severe anemia if they have significantly increased menstrual bleeding compared to their baseline. Anemia from any cause can result in the same symptom of feeling tired all the time. Causes of anemia may include menstrual bleeding in women, internal stomach or intestine bleeding in men or women, excessive nose bleeding, any kind of leukemia or blood cancer, defect in blood cells, problems with bone marrow or certain nutritional deficiencies.
  2. Low thyroid: Low thyroid is a very common cause of what makes you tired all the time. Symptoms of low thyroid can be very complex and bizarre but many people simply wonder, “I’m tired all the time what’s wrong with me?” Thyroid hormone is a natural catalyst in our body. It influences the speed of almost all chemical reactions in our body. Low thyroid hormone can slow down all energy production and utilization in the body and make you feel like you have no energy. With the low energy utilization, you naturally feel tired all the time. Disease of the thyroid gland can affect all or most of your organ symptoms. In addition to feeling tired all the time, you may also feel cold all the time. You may also fell sleepy and drowsy all the time. You may feel like you can’t focus on task at hand. You may also have trouble remembering details about your work.
  3. Sleep apnea: Sleep apnea can make you feel tired all the time even with enough sleep. When you have sleep apnea, the quality of your sleep goes down. When you go into deep sleep, your airway collapses and you wake up momentarily before falling asleep again. You may go through many instances of these sleep-wake cycles during the night and may not even know about them. The end result is severe disruption of sleep cycle. That can make you tired all the time during the day. You may also have trouble staying awake while at work. Untreated sleep apnea can cause problems with your blood pressure and breathing, and may eventually lead to heart failure.
  4. Kidney failure: Feeling tired all the time may be the only major symptom of kidney failure if it develops slowly. Kidney failure can happen quickly over a few days or can take years to develop. A rapid kidney failure can have many worrisome symptoms but a slow developing kidney failure can go undetected for years. When you ask yourself, “Why am I so tired all the time this year when I could do so much last year?”, do not dismiss it as just a symptom of getting old. In addition to symptoms of lethargy, slow developing kidney failure can cause decreased appetite, nausea, itching and muscle cramps.
  5. Obesity hypoventilation syndrome: If you are so tired all the time and putting on weight, you need to be concerned about obesity hypoventilation syndrome. When you gain so much weight that it starts to interfere with your lung ventilation, you have obesity hypoventilation syndrome. It does not happen in everyone who is obese but obesity is obviously the biggest risk factor for developing obesity hypoventilation syndrome. When your lungs are unable to move enough air, you start to accumulate carbon-dioxide in your blood. A high carbon-dioxide makes your blood acidic. You may also develop low oxygen levels in your blood as your carbon dioxide levels go up. As a end result, you become tired all the time, drowsy all the time and may become confused at times.
  6. Diabetes: If you are tired all the time and hungry, you need to think about diabetes. Feeling tired, hungry and thirsty is a common way of presenting with undiagnosed diabetes. It can happen with both type 1 or type 2 diabetes. When your blood sugar goes up, you lose a lot of water in your urine. It makes you very dehydrated and weak. Complications from your untreated diabetes can lead to severe metabolic derangement and you can go from feeling tired all the time to severe lethargy and even coma.
  7. Adrenal insufficiency: Tired all the time, low blood pressure, weight loss, loss of appetite and muscle weakness are some of the common symptoms of adrenal insufficiency. In adrenal insufficiency, your adrenal gland fails to produce enough hormone to properly regulate your body. Just like thyroid hormone deficiency, adrenal insufficiency can take a long time to develop. These slowly developing symptoms may go undetected for years until you are so tired all the time that you can barely walk.
  8. Certain heart diseases: You may feel tired all the time from certain types of heart failure but you usually also have some other symptoms. If you are tired all the time and run out of breath easily with minimal activity, you need to think about heart disease.

Tired all the time: blood tests your doctor needs to order

Simple blood tests can detect many of things that make you tired all the time. You doctor orders common blood tests first and then go on to order more specific tests. However, if you have any symptom that point towards a particular diagnosis, you need to be proactive and ask your doctor about that particular test so that you can get diagnosed early.



  1. Complete blood count or CBC: It can help your doctor make sure you don’t have anemia or any other blood disorder.
  2. Comprehensive metabolic panel or CMP: It can detect diabetes as well as kidney failure.
  3. Thyroid Stimulating hormone or TSH: It can detect thyroid problems.
  4. Arterial blood gas or ABG: It can detect obesity hypoventilation syndrome.
    Cortisol level with ACTH stimulation test: This test is designed to detect adrenal insufficiency.

Tired all the time: other diagnostic tests

  1. Sleep study: This will help detect obstructive sleep apnea.
  2. Heart tests: Several heart tests may be done to detect possible heart problems if you have any chest pain or shortness of breath in addition to feeling tired all the time.

Tired all the time but blood tests normal

When you are tired all the time with no motivation and no energy but all your blood tests, heart tests and sleep study come back normal, you need to think about depression, anxiety, stress related or mental health issues. It is important that you wait until all medical causes of fatigue symptoms are ruled out before you consider these conditions.